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Fortifying Irondequoit Creek's banks

Water power 

Fortifying Irondequoit Creek's banks

Irondequoit Creek in Powder Mills Park.

PHOTO BY MARK CHAMBERLIN

Irondequoit Creek in Powder Mills Park.

Water is a powerful natural force, with enough brute strength to wash away cities and the persistence to wear down rock. And in humankind's more practical moments, people have figured out how to work with that force — think of the mills and hydroelectric plants powered by swift streams and waterfalls.

But humanity's relationship with water is complex, and people have also tried to tame water by battling its natural tendency to flow, spread out, and wear down.

That's the case with Irondequoit Creek, which starts in the Ontario County hamlet of Fishers and passes through heavily developed areas before emptying into Irondequoit Bay. Government officials and private landowners have been trying for at least a couple of decades to keep the stream from eating away its own banks.

This spring, construction will begin on a new round of projects to shore up the stream's banks. Monroe County will work on four sites — two in Ellison Park and two in Powder Mills Park — while the YMCA of Greater Rochester addresses a problem area in its Camp Arrowhead, which is surrounded by Powder Mills Park.

The projects are, in a sense, property protection efforts. The eroding streambanks mean lost property and can become safety hazards.

But there's a bigger picture: the projects will also improve Irondequoit Creek's environmental health. And that's critical because the stream provides important habitat and spawning grounds for steelhead and brown trout, which draw a lot of anglers to the creek.

"It's one of the few coldwater tribs [tributaries] of Lake Ontario," says Ron Mitchell, manager of the Fish Hatchery at Powder Mills, which each year releases 18,000 steelhead and brown trout into the creek.

The issue is silt and sediment generated from the erosion. As the creek wears down its banks, it picks up and carries the sediment along until the sediment settles somewhere along the way. And the sediment can cover up and basically suffocate the trout eggs in the creek, Mitchell says, which makes it harder to establish and preserve breeding populations.

The county worked with the State Department of Environmental Conservation to select the Ellison and Powder Mills sites, says David Rinaldo, the county's deputy parks director. They concluded that the four locations — one includes a heavily-worn spot in Ellison known as Dog Beach — are in the worst shape. The county projects will be funded by a $250,000 grant.

"We know we have 3,000 feet of streambank that are bad and need to be addressed, but that's not all," Rinaldo says. "That's a starting number and we could keep going quite a bit beyond that if we had the resources."

Bank erosion is a pretty common problem in streams everywhere, and for the most part, it's nature at work.

"The natural process is for the stream to cut down all the high points in the topography and make a plain," says William Coon, a hydrologist with the US Geological Survey who developed a streamflow model for Irondequoit Creek. "That's what it wants to do. That's why you have floodplains adjacent to channels."

But the creek is not the only local stream with erosion problems. The Town of Chili and the Monroe County Soil and Water Conservation District have worked together to shore up sections of Black Creek. And that work was aimed partly at reducing the amount of erosion-linked sediment in the water.

Black Creek is a major tributary of the Genesee River, and so the sediment it carries is ultimately fed into Lake Ontario. That sediment adds to existing water-quality problems in the near-shore area of the lake; it carries nutrients that encourage algae growth and it clouds the water, making it difficult for fish and other desirable organisms to thrive.

In Irondequoit Creek, the problems caused by sediment come back to trout and salmon, which are generally at the top of their respective aquatic food webs. Both spawn in the stream, and the sediment can interfere with that activity.

But it can also hurt them in another way: the sediment can blanket the areas where insects eaten by the fish — by trout especially — reproduce. In short, it can disrupt the food supply of the fish.

There's no single factor driving the erosion at Irondequoit Creek; it involves natural and human influences.

When a stream starts eating away at its banks, that process actually encourages additional erosion. The deteriorating banks begin to redirect the flow and force of the water outward instead of downward into the bottom of the channel.

And surges of water tend to accelerate erosion. Development can play a role, since hard surfaces such as roads, parking lots, and roofs can direct water from rainstorms into streams.

Towns in the area that drains into the Irondequoit Creek have taken steps to rein in that runoff. For several years, they've had laws on the books that require developers to install storm water controls as part of new construction projects.

Those controls include retention ponds and landscaping approaches meant to slow down water so it can be absorbed into soil.

Shifts in precipitation patterns, brought on by climate change, also play a role in the erosion. Overall, the amount of precipitation that the Rochester area gets hasn't changed much, but more frequently it's coming in heavy bursts. And those downpours tend to be more intense than in the past.

"On an observation basis, I think we've seen more what we call flashy storms, where the water rises very quickly within the creek, within the parks, more so than in the past," says Monroe County's Rinaldo.

There is one area in Ellison Park where the erosion problems have a more direct cause: Dog Beach. For years, many park visitors let their dogs illegally run in and out of the creek at that spot. The county and DEC have been eager to fix the damage at Dog Beach, which was part of the reason why county officials supported a dog park at Ellison.

Past projects to improve Irondequoit Creek's erosion and sediment problems have paid off.

The creek used to carry large amounts of sediment into Irondequoit Bay, which contributed to the bay's past water-quality problems. The sediment would fill in the gravelly bottom, used by many fish and insects for spawning.

And like sediment flowing into other near-shore areas in Lake Ontario, the sediment in Irondequoit Creek clouded the water and carried nutrient pollutants that encourage algae growth.

But two projects helped to significantly reduce the problem, so much so that the US Geological Survey is reintroducing a fish species, lake cisco, that spawns in the bottom of the bay. The spawning grounds had previously been inundated with sediment.

In the late 1990's, the Town of Penfield reinforced an eroding sand bluff along Irondequoit Creek in Channing H. Philbrick Park, then known as Linear Park. The eroding bluff was contributing an estimated 15,000 tons of sediment to the bay each year, according to a summary from the project's engineer, MRB Group.

The project, which was done in two phases and completed in 2004, was expected to halve the amount of sediment that the creek was carrying into the bay, the summary says.

Another project involved a detention system in the Ellison wetlands, meant to hold back the stream's surges during storms. That allowed sediment to settle out in the wetland, a natural filter, and then flow more gradually into the bay.

As for the current batch of Irondequoit Creek projects, it's unlikely they'll be the last. The same can be said for other important streams where erosion has been an issue.

"For probably 150 years, sedimentation issues have been a problem and I don't see that changing," says the hydrologist Coon. "We deal with what the current situation is and try to reduce the loads as much as we can."

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